Power tools commonly use pneumatic or hydraulic mechanisms for powering the tool. For example, impact wrenches use rotational motors having rotors that receive pressurized air or fluid to produce a rotational force to a work piece. The pressurized air or fluid causes rotation of the rotor of the motor.
Many times, a user may desire to reverse the rotational direction of the power tool, for example, when the work piece is left-hand threaded or when the user desires to loosen the work piece instead of tighten it with the power tool. Conventional power tools include reversing mechanisms that change the rotational direction of the tool so that the user can switch between clockwise and counterclockwise rotational directions of the tool. This is typically accomplished by an internal valve assembly that switches the internal direction of the pressurized air or fluid from one side of the rotor to the other.
Similarly, conventional power tools include mechanisms to control the power output of the tool by controlling the amount of pressurized air or fluid that effectively turns the rotor. However, such power tools cannot independently regulate the power output of only one of either the clockwise or counterclockwise rotational directions of the tool. Rather, such tools regulate both the clockwise and counterclockwise directions without discretion. Yet, it is often desirable to regulate rotational power output of the clockwise and counterclockwise rotational directions differently. For example, it is often desirable to require less power when tightening a work piece (such as when the tool is operated in the clockwise direction), and unrestricted or maximum power when loosening a work piece (such as when the tool is operated in the counterclockwise direction). However, since some power tools regulate power output in both rotational directions without differentiation, the conventional systems cannot control power output of only one of the rotational directions. Moreover, tools often regulate power using the same mechanism as the forward and reverse mechanism, causing the user to confuse the tactile feedback from the forward/reverse mechanism as that of the power regulator.
Moreover, some power tools typically regulate power by redirecting and releasing a certain amount of pressurized air delivered to the rotor of the motor, thus decreasing the amount of pressurized air that effectively rotates the rotor of the motor. The released air pressure is typically released from the tool to the environment, commonly known as “bleed off.” Such bleed off air is thus wasted and unused, thus causing increased costs and time (e.g., an air compressor must run more often due to the released and unused air).